Precipitation process of 7-aminocephalosporanic acid (7-ACA)

ABSTRACT

A process in the isolation of 7-aminocephalosporanic acid (7-ACA) from an alkaline, neutral or slightly acidic medium in the presence of an additive, e.g. selected from the group comprising organic carboxylic acid esters, polymeric glycols, polyacryls, amines and polyamines, melamin-formaldehyde resins or amino acids and esters thereof to obtain 7-ACA agglomerates and or rosettes.

[0001] The present invention relates to 7-aminocephalosporanic acid(7-ACA)

[0002] 7-ACA is a key intermediate compound in the synthesis of manysemi-synthetic cephalosporin antibiotics. It may e.g. be produced fromcephalosporin C by cleavage of the amide function in position 7 of thering system

[0003] e.g. chemically, e.g. by conversion of the amide function into animide chloride function which may be hydrolysed to give 7-ACA, e.g. in astrong acidic medium and precipitating 7-ACA, e.g. by adjustment of thepH (around the isoelectric point), e.g. by addition of a base; 7-ACA maybe isolated in the form of rosettes and agglomerates;

[0004] or enzymatically, e.g. by action of an acylase; or by conversionof cephalosporin C into glutaryl-7-amino-cephalosporanic acid, e.g. byaction of a D-amino acid oxidase, enzymatically hydrolysing aglutaryl-7-amino cephalosporanic acid to obtain 7-ACA, e.g. in a basicmedium, neutral or slightly acidic medium, optionally purifying thereaction solution with an appropriate ion exchanger or absorber resin,and precipitating 7-ACA, e.g. by adjustment of the pH (around theisoelectric point), e.g. by addition of an acid, e.g. HCl. In that caseprecipitated 7-ACA may be, however, in the form of very small, loose,needle-like crystals difficult to be isolated. Increasing purity of7-ACA may result in still smaller crystals and addition of an organicsolvent, e.g. a, e.g. lower, alcohol, e.g. methanol or a ketone, e.g.acetone, to the reaction mixture before the isolation of 7-ACA, whichmay improve the yield, again may result in considerably smallercrystals.

[0005] The present invention provides a process, e.g. which may bycarried out on technical scale, wherein agglomerates or rosettes of7-ACA may be formed on 7-ACA precipitation from an alkaline, neutral orslightly acidic medium which substantially improves isolation of 7-ACA,e.g. by filtration and centrifugation and additionally, 7-ACA obtainedaccording to the present invention may be dried more quickly, e.g. whichmay result in a smaller amount of by-products compared with 7-ACAobtained according to a prior art process.

[0006] In one aspect the present invention provides a process for theproduction of rosettes or agglomerates of 7-ACA, e.g. of formula I,characterized in, that 7-ACA is precipitated from an alkaline, neutralor slightly acidic medium in the presence of an additive, e.g. selectedfrom a group comprising e.g. groups as defined below.

[0007] An additive according to the present invention may be a compoundwhich on addition in a precipitation process of 7-ACA may causeformation of agglomerates and/or rosettes includes e.g. organiccarboxylic acid esters,e.g. of formula

R₁—COO—R₂  II,

[0008] polymeric glycols, e.g. polyethylene and polypropylene glycols,e.g of formula

HO—(CHR₁—CHR₂)_(k)—OH  III,

[0009] polyacryls, e.g. of cationic, anionic or non-ionic polyacryls,including e.g. polacrylamides, e.g. of formula

—[CHR₁—CR₂(COXR₃)]_(n)—  IV,

[0010] amines and polyamines, e.g. of formulae

—[CH₂—CHR₆—CH₂—N⁺R₁R₂—]_(n)—  Va

R₂R₄N—(CH₂—CH₂X)_(n)—R₅  Vb

[R₁—X—(CH₂)_(m)]₃N  Vc

[0011]

[0012] melamin-formaldehyde resins, e.g. of formula

[0013] e.g. of a molecular weight of up to 1,000,000, e.g. 500,000 andamino acids and esters thereof, e.g. of formula

R₁₀—CH—(NR₂R₄)—COOR₁  vm

[0014] e.g. including mixtures of individual additives, e.g. asdescribed above. An additive may be preferably an amino acid and esterstherof, e.g. an amino acid such as e.g. lysine.

[0015] In formulae II, III, IV, Va, Vb, Vc, VIa, VIb, VII and VIII

[0016] R₁, R₂, R₄ and R₅ independently of each other denote hydrogen,alkyl or aryl;

[0017] k denotes a whole number from 2 to 200;

[0018] X denotes —O— or —NR₁—;

[0019] R₃ has the meaning of R₁ or denotes a group of formula—(CR₂R₄)_(m)—Z

[0020] Z denotes amino, a sulphonyl group or a carboxylic acid group,e.g. of formulae

[0021] m denotes a whole number from 0 to 6;

[0022] n denotes a whole number from 2 to 200,000;

[0023] R₆ represents hydrogen or hydroxy;

[0024] R_(7a), R_(7b), R_(7c), R_(7d) and R_(7e) independently of eachother denote hydrogen, —CH₂OH; or a group of formula

[0025] and R₁₀ denotes hydrogen, alkyl, aryl or a group of formula—(CH₂)_(m)—X—R₅. If not otherwise defined herein, alkyl includes e.g.(C₁₋₂₂)alkyl, such as (C₁₋₈)alkyl, e.g. lower alkyl, such as (C₁₋₄)alkyland aryl includes e.g. phenyl, naphthyl, such as phenyl. Alkyl and arylincludes unsubstituted alkyl and aryl and alkyl and aryl substituted bygroups which do not cause the formation of another compound than 7-ACAunder precipitation conditions of 7-ACA in alkaline, neutral andslightly acidic medium; e.g. which do not chemically react with 7-ACA toform another compound. Preferably alkyl includes lower alkyl; arylincludes phenyl and substituted aryl includes substituted aryl, e.g.phenyl by hydroxy or alkyl e.g. lower alkyl. Amino includesunsubstituted amino or ammonium and substituted amino and ammonium, e.g.by alkyl.

[0026] In another aspect the present invention provides a process forthe isolation of 7-ACA, e.g. of formula I from slightly acidic, neutralor alkaline solution, characterized in that 7-ACA is precipitated in thepresence of an additive, e.g. selected from a group comprising groups ase.g. defined above, e.g. in an amount of 1 ppm to 10% in the slightlyacidic, neutral or alkaline solution.

[0027] A process of the present invention may be carried out as follows:

[0028] 7-ACA may be precipitated from slightly acidic, neutral oralkaline solution of 7-ACA, including e.g. a solution of 7-ACA in asolvent to which an acid is to be added for precipitating 7-ACAtherefrom, e.g. a solution of 7-ACA having a pH which is above theisoelectric point of 7-ACA in a solvent; which is in contrast to astrong acidic solution of 7-ACA to which a base is to be added forprecipitating 7-ACA therefrom, e.g. a solution of 7-ACA having a pHwhich is below the isoelectric point of 7-ACA in a solvent in thepresence of an additive, e.g. selected from a group comprising groups asdefined above, e.g. in the presence of seed crystals of 7-ACA, e.g. inthe form of rosettes and/or agglomerates by addition of an acid.

[0029] An additive according to the present invention is known or may beproduced analogously to known, e.g. conventional processes. A slightlyacidic, neutral or alkaline solution of 7-ACA may be obtained e.g. by anenzymatic process as defined above. The concentration of 7-ACA inslightly acidic, neutral or alkaline solution is not critical and mayvary within a broad range, including e.g. a range of, e.g. ca., 5 to 60g/l, such as 10 to 50 g/l. An additive may be e.g. added to 7-ACA inslightly acidic, neutral or alkaline solution before addition of an acidor simultanously.

[0030] The amount of an additive according to the present invention isnot critical, e.g. for ecological reasons a low amount of an additive,e.g. ca., 1 ppm to 10% (v/v) in respect with the amount of 7-ACAsolution may be appropriate. In case of use of non-polymeric additives,such as e.g. organic esters as an additive an amount of, e.g. ca., 1% to10% may be appropriate; in case of use of an amine, amino acid or esterthereof an amount of, e.g. ca., 0.01% to 10%, such as, e.g. ca., 0.05%to 5% may be appropriate, in case of use of a polymeric additives, e.g.such as polyacryls, polyamines, polymeric glycols e.g. ca. 1 to 100 ppmmay be appropriate. Seed crystals of 7-ACA, e.g. as defined above, maybe added to a solution or to a resulting crystal suspension of 7-ACAeither prior to or simultaneously with an acid. The process of thepresent invention may be carried out batchwise or continuously, in abroad temperature range, including e.g. −15° to 40° C., such as 0° to25° C.

[0031] An appropriate acid includes inorganic acids, e.g. sulphuricacid, hydrochloric acid or phosphoric acid, or organic acids, e.g.acetic acid.

[0032] The acid is added in an amount which is sufficient that 7-ACA,e.g. in high yields, is precipitated from the solution. A pH of thereaction mixture of around the isoelectric point of 7-ACA in a solventmay be convenient, including, but not limited to, a pH of 2.5 to 6, suchas 3.5 to 5.5.

[0033] 7-ACA may precipitate on acid addition, e.g. in crystalline form.A crystall suspension obtained may be stirred, e.g. under adjustment ofthe pH around the isoelectric point in order to complete precipitation,e.g. under cooling.

[0034] 7-ACA obtained, e.g. in crystalline form and in the form ofagglomerates and/or rosettes may precipitate and may be isolated, e.g.as conventional, such as by filtration, centrifugation, washed asappropriate and dried. The drying temperatures may be low, e.g. 40° to50°, e.g. under vacuum, and the drying times may be short, e.g. ca. 5 to30, such as 10 to 20 hours. The presence of an additive according to thepresent invention in the precipitation of 7-ACA may surprisingly resultin the formation of agglomerates or rosettes of 7-ACA, even in case thatan organic solvent such as an alcohol or a ketone is present in thesolution and even in case that highly pure 7-ACA, e.g. purified via anabsorber resin purification, e.g. with Amberlite XAD 1600^(R),XE-714^(R), Dianion HP21^(R), Sepabeads SP825^(R), SP850^(R)), or via anion exchanger purification, e.g. with IRA 420^(R). The filtration timeof a 7-ACA crystal suspension in the presence of an additive obtainedaccording to the present invention may considerably be reduced incomparison with the filtration time of 7-ACA obtained without thepresence of an additive, e.g. from ca. 15 minutes to 1 minute and evenbelow, such as of ca. 0.4 minutes.

[0035] The following examples are intended to illustrate the invention.Temperatures are given in degree Celsius and are uncorrected.

[0036] 7-ACA is 7-aminocephalosporanic acid, e.g. of formula I.

EXAMPLES 1 to 14 General Procedure

[0037] 142 of water and 2.2 g of 7-ACA in form of rosettes and/oragglomerates as a seeding material are placed in a precipitationreactor, and the pH is adjusted to 5.5 with 1 N NaOH. A solution of 25 gof 7-ACA in the form of a sodium salt, 708 ml of water with or withoutmethanol (in ml) as set out in TABLE 1 below having a pH of ca. 7.0 ismixed with an additive as set out in TABLE 1 below and the mixtureobtained is added dropwise to the mixture in the reactor under stirring,over the course of ca. 25 minutes at ca. 18°. During addition the 7-ACAmixture into the mixture in the precipitation reactor the pH of thereaction adjusted to 5.5 by addition of 20% sulphuric acid. The pH of asuspension obtained is adjusted to 4.0 , the suspension is cooled to 0°and stirred for ca. 1 hour. Crystalline 7-ACA obtained is filtrated off,washed with 120 ml of water, 120 ml of 70% methanol and 120 ml ofmethanol and dried in a vacuum (ca. 10 mbar) for ca. 16 hours at ca.50°. The filtration times (in minutes) are summarised in TABLE 1 below.TABLE 1 Methanol Filtration Example [ml] Additive time [min] 1 212 Noadditive 15 2 212 Polyacryl (amide) 2 e.g. 6.5 ml 1% solution ofP3-Ferrocryl 7262^(R) 3 0 Polyacryl (amide) 1.6 e.g. 6.5 ml 1% solutionof P3-Ferrocryl 7262^(R) 4 0 Organic carboxylic acid ester 2.1 e.g. 49.5ml Ethyl acetate 5 0 Organic carboxylic acid ester 1.1 e.g. 10.6 mlButyl acetate 6 212 Organic carboxylic acid ester 2.4 e.g. 13.8 ml Butylacetate 7 212 Organic carboxylic acid ester 2.9 e.g. 64.4 ml Ethylacetate 8 177 Polyacryl (amide) 0.8 e.g. 0.8 ml 1% solution of Cysep2411^(R) (Cytec) 9 177 Polyamine 0.3 e.g. 0.8 ml 1% solution of C592^(R) (Cytec) 10 177 Polyamine 0.4 e.g. 0.8 ml 1% solution of C567^(R) (Cytec) 11 177 Polymeric glycol 2.1 e.g. 3.2 ml 1% solution ofPEG 300^(R) (Fluka) 12 177 Amine 3.2 e.g. 2.4 ml 1% solution oftriethylene tetramine 13 177 Amine 3.2 e.g. 0.8 ml 1% solution oftris-(2-amino-ethyl)amine 14 177 Amino acid 3.3 e.g. 0.8 ml 1% solutionof 1-lysine

EXAMPLES 15 to 18 General Procedure

[0038] A solution of 20.8 g of 7-ACA in the form of a sodium salt, 500ml of water with or without methanol (in ml) as set out in TABLE 2 belowhaving a pH of ca. 7.5 is placed in a precipitation reactor at roomtemperature. and mixed with an additive as set out in TABLE 2 below. ThepH of the mixture obtained is adjusted to 5.5 by addition of 20%sulphuric acid under stirring and kept for ca. 20 minutes. The pH of asuspension obtained is adjusted to 3.8, the suspension is cooled to 0°and stirred for ca. 1 hour. Crystalline 7-ACA obtained is filtrated off,washed with 100 ml of water, 100 ml of 70% methanol and 100 ml ofmethanol and dried in a vacuum (ca. 10 mbar) for ca. 16 hours at ca.50°. The filtration times (in minutes) are summarised in TABLE 2 below.TABLE 2 Methanol Filtration Example [ml] Additive time [min] 15 150 Noadditive 14 16 100 Organic carboxylic acid ester 1.5 e.g. 9 ml 1 Butylacetate 17 150 Polyacryl (amide) 1.4 e.g. 6.5 ml 1% solution ofFerrocryl 7262^(R) (Henkel) 18 150 Polyacryl (amide) 3.0 e.g. 3.2 ml 1%solution of Rohafloc KF760^(R) (Rhöm)

1. A process for the production of rosettes or agglomerates of 7-ACA offormula

characterized in that 7-ACA is precipitated from an alkaline, neutral orslightly acidic medium in the presence of an additive.
 2. A process forthe isolation of 7-ACA from slightly acidic, neutral or alkalinesolution, characterized in that 7-ACA is precipitated in the presence ofan additive.
 3. A process according to any one of claims 1 or 2,characterized in that an additive is selected from the group comprisingorganic carboxylic acid esters, polymeric glycols, polyacryls, aminesand polyamines, melamin-formaldehyde resins or amino acids and estersthereof.
 4. A process according to any one of claims 1 to 3characterized in that an additive is an amino acid.
 5. A processaccording to any preceding claim, characterized in that the additive ispresent in an amount of 1 ppm to 10% in the alkaline, neutral orslightly acidic medium containing 7-ACA.
 6. A process for the isolationof 7-aminocephalosporanic acid (7-ACA) from slightly acidic, neutral oralkaline solutions thereof by precipitation, characterised in that a)organic esters of the general formula R₁—COO—R₂  II  wherein R₁ and R₂are the same or different and represent hydrogen, lower alkyl, phenyl,hydroxyphenyl or lower alkylphenyl; b) polymeric glycol compounds,preferably polyethylene and polypropylene glycol derivatives, of thegeneral formula HO—(CHR₁—CHR₂)_(k—OH)  III  wherein R₁ and R₂ are asdefined above, and k denotes a whole number from 2 to 200; c) polyacrylderivatives of cationic, anionic or non-ionic character, of the generalformula —[CHR₁—CR₂(CO.XR₃)]_(n)—  IV  wherein X denotes —O— or —NR₁— andR₃ denotes R₁ or —(CR₂R₄)_(m)—Z, wherein Z denotes

 m is a whole number from 0 to 6, n is a whole number from 2 to 200,000and R₁, R₂, R₄ and R₅ are the same or different and represent hydrogen,lower alkyl, phenyl, hydroxyphenyl or lower alkylphenyl; d) (poly)aminesof the general formulae—[CH₂—CHR₆—CH₂-N⁺R₁R₂—]_(n)—  VaR₂R₄N—(CH₂—CH₂X)_(n)—R₅  Vb[R₁—X—(CH₂)_(m)]₃N  Vc

 wherein m, n, R₁, R₂, R₄ and R₅ are as defined above and R₆ denoteshydrogen or OH; e) derivatives based on melamine-formaldehyde resins ofthe general formula

 wherein R_(7a), R_(7b), R_(7c), R_(7d) and R_(7e) are the same ordifferent and denote hydrogen, CH₂OH, or a group of formula

f. amino acids and esters thereof, of the general formulaR₁₀—CH—(NR₂R₄)—COOR₁  VIII  wherein R₁₀ denotes hydrogen, alkyl, aryl ora group of formula —(CH₂)_(m)—X—R₅ and the remaining substituents are asdefined above, are added during precipitation.